A police officer patrols outside the voter registration center in Kabul that was attacked by militants.
ISIS claimed the attack, saying it targeted Shiite "apostates".
Additional reporting from Newsy affiliate CNN.
That vote is due to be followed by a presidential election in 2019.
Afghan officials say the toll from a suicide bombing in Kabul that targeted a voter registration center has climbed to at least 31 killed and 54 wounded.
The extremist group is opposed to democratic elections.
The besieged group has nowhere near the same power or hold of territory in Afghanistan that the Taliban has, but it has still been able to conduct attacks in urban areas of the country. Majro added that 119 people were wounded in Sunday's attack, among them 17 children and 52 women. "Everyone had come to get their identity cards", bystander Bashir Ahmad told Reuters. More than 7,000 voter registration centres have been set up across Afghanistan to handle about 10 million registrations in a process that has been repeatedly disrupted by technical and organisational problems.
Officials said that even provincial capitals were struggling to open all voter registration centers.
ISIS claimed responsibility for the bombing, in a statement distributed through Telegram.
"This senseless violence shows the cowardice and inhumanity of the enemies of democracy and peace in Afghanistan", US ambassador John Bass wrote on Twitter.
In Afghanistan, a suicide bomber has killed at least 57 people registering to vote at a center in Kabul, according to a Public Health Ministry spokesperson.
"We are grieved at the loss of precious innocent lives in this brutal act of terrorism".
U.S. Acting Secretary of State John J. Sullivan said in a statement on April 22 that he "strongly" condemned the attack and extended the U.S. government's "deepest condolences to the families of the victims who have suffered an immeasurable loss". A North Atlantic Treaty Organisation spokesman said the child had been taken to hospital and was in a stable condition. "Our resolve for fair and transparent election will continue and terrorists won't win against the will of the Afghan people".
Afghanistan's interior minister this year told the BBC that both IS and the Taliban were targeting civilians to provoke people against the government and create chaos.